Keratin is composed of several urea soluble peptides. The site of synthesis of these individual peptides within the viable epidermis will be determined. By comparing peptide fragments produced by trypsinization and cyanogen bromide, the larger keratin peptides will be analyzed for homologous fragments and reduplications. The keratin peptides will be isolated from the ichthyoses, and psoriasis to determine whether differences in mobility reflect transcriptional or post-translational change. The keratin peptides in other keratinizing tissues: esophagus, mouth, vagina and cervix will be compared with epidermal keratins. The keratin in metaplasia and dysplasia of the cervix will be analysed.